Microwave oscillators based on planar technology are known in which the oscillation generator and conductor structures for forming resonators, microwave conductors, filters, and the like are situated on a common substrate. However, for specific applications, e.g., a distance warning radar in motor vehicles, microwave oscillators based on hollow conductor technology are preferred, so that it is possible to satisfy the requirements for quality and performance of the oscillator.
A microwave oscillator known from the related art for a motor vehicle distance warning radar has a hollow conductor or oscillator body in the form of a metallic housing, which is screwed onto the radar device and is electrically connected by hand soldering using a lead. The oscillation generator is formed by a Gunn device, which projects into the oscillator body from below. The upper end of the oscillator body is closed by an insulating body to which a printed circuit board is attached. The Gunn device is supplied with direct voltage by a pin-like filter element, known as a bias choke, which extends from the printed circuit board through the interior of the oscillator body to the top of the Gunn device and acts as a lowpass filter. The printed circuit board includes a capacitive network, which is used to suppress voltage spikes when switching the oscillator on and off.